Digital flat panel x-ray receptor positioning in diagnostic radiology

ABSTRACT

A digital, flat panel, two-dimensional x-ray detector moves reliably, safely and conveniently to a variety of positions for different x-ray protocols for a standing, sitting or recumbent patient. The system makes it practical to use the same detector for a number or protocols that otherwise may require different equipment, and takes advantage of desirable characteristics of flat panel digital detectors while alleviating the effects of less desirable characteristics such as high cost, weight and fragility of such detectors.

REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of parent application Ser.No. 09/449,457 filed on Nov. 25, 1999 (due to issue as U.S. Pat. No.6,282,264 on Aug. 28, 2001), which in turn is a continuation-in-part ofSer. No. 09/413,266 filed on Oct. 6, 1999 (abandoned). This applicationhereby incorporates by reference the entire disclosure of each of saidparent applications.

FIELD

This patent specification is in the field of radiography and pertainsmore specifically to the field of x-ray equipment using a digital flatpanel detector.

BACKGROUND

Medical diagnostic x-ray equipment has long used x-ray film containedinside a lightproof cassette, with the cassette at one side of thepatient and an x-ray source at the opposite side. During exposure,x-rays penetrate the desired body location and the x-ray film recordsthe spatially varying x-ray exposure at the film. Over the years,medical experience has developed and optimized a variety of standardprotocols for imaging various parts of the body, which require placingthe film cassette in different positions relative to the patient. Chestx-rays, for example, are often performed with the patient standing,chest or back pressed against a vertical film cassette. Imaging of thebones in the hand might be done with the cassette placed horizontally ona surface, and the hand placed on top of the cassette. In anotherprocedure the patient might cradle the cassette under an arm. Acollection of such standard protocols is described in Merrill's Atlas ofRadiographic Positions and Radiologic Procedures, by Philip W.Ballinger, et. al., 9th edition, published by Mosby-Year Book,Incorporated, hereby incorporated by reference.

Advances in digital x-ray sensor technology have resulted in thedevelopment of arrays of sensors that generate electrical signalsrelated to local x-ray exposure, eliminating film as the recordingmedium. An example is discussed in U.S. Pat. No. 5,319,206, incorporatedherein by reference, and a current version has been commerciallyavailable from the assignee of this patent specification. Such digitalarrays are often called flat panel x-ray detectors, or simply flat paneldetectors, and offer certain advantages relative to x-ray film. There isno need for film processing, as the image is created and comes from thecassette in electronic digital form, and can be transferred directlyinto a computer. The digital format of the x-ray data facilitatesincorporating the image into a hospital's archiving system. The digitalflat panel detectors or plates also offer improved dynamic rangerelative to x-ray film, and can thus overcome the exposure rangelimitations of x-ray film that can necessitate multiple images to betaken of the same anatomy. On the other hand, digital flat paneldetectors currently have a higher capital cost than film cassettes, andare more fragile. They often incorporate lead shielding to protectradiation-sensitive electronics, and can be heavy. If they are connectedto a computer with a cable, cable handling needs to be taken intoconsideration when moving the cassette and/or the patient.Alternatively, the cassette can be self-contained, as for example inU.S. Pat. No. 5,661,309, in which case it includes a power supply andstorage for the image information, increasing its weight and possiblysize. Such detectors commonly are used in a system comprising a suitableanti-scatter or Bucky plate.

The high initial cost of the digital detector can hinder outfitting ofan x-ray room with multiple detectors pre-mounted in a variety ofpositions, such as a vertically-mounted unit for chest, and a horizontalunit under a bed. The fragility, weight, and initial cost of the unitsmake them difficult to use in procedures where the patient cradles thedetector. The unique characteristics of digital flat panel detectors canmake conventional film cassette holders impractical for use with flatpanel detectors.

A number of proposals have been made for x-ray systems using flat paneldetectors. A C-arm arrangement has been offered under the name Traumexby Fisher Imaging Corporation of Denver, Colo., with the participationof a subsidiary of the assignee hereof. Another C-arm arrangement isbelieved to be offered under the name ddRMulti-System by Swissray, andliterature from Swissray has stated that a ddRCombi-System is scheduledfor launch in early 2000 and would offer the same functionality as theddRMulti-System but would use existing third party suspension equipmentfor the x-ray tube (an illustration therein appears to illustrate adetector arrangement mounted for vertical movement on a structureseparate from a ceiling-mounted x-ray tube support. A vertically movingand rotating image intensifier appears to be illustrated in FIG. 3 ofU.S. Pat. No. 4,741,014. U.S. Pat. Nos. 5,764,724 and 6,155,713 proposeother configurations.

A number of other proposals have been made for positioning x-ray filmcassettes but the different physical characteristics and requirements offlat panel detectors systems do not allow for direct application of filmcassette positioning proposals. For example, U.S. Pat. No. 4,365,344proposes a system for placing a film cassette in a variety of positionsand orientations relative to a floor mounted x-ray source support. U.S.Pat. No. 5,157,707 proposes moving a film cassette to differentpositions relative to a ceiling mounted x-ray tube support to allowtaking AP (anterior-posterior) and lateral chest images of a patientsitting on a bed. The figures of Swedish patent document(Utlaggningsskrift [B]) 463237 (application 8900580-5) appear to show asimilar proposal as well as a proposal to mount the x-ray cassette andthe x-ray source on the same structure extending up from the floor. U.S.Pat. 4,468,803 proposes clamping an articulated support for a filmcassette on a patient table, and U.S. Pat. No. 5,920,606 proposes aplatform on which a patient can step and into which a film cassette canbe inserted to image a weight-bearing foot.

With a view to the unique characteristics and requirements of digitalflat panel detector systems, it is believed that a need exists toprovide a safe, reliable, convenient and effective way to position suchsystems for a wide variety of imaging protocols, and this patentspecification is directed to meeting such a need.

SUMMARY

An exemplary and non-limiting embodiment comprises a digital, flatpanel, two-dimensional x-ray detector system that is not mechanicallycoupled to x-ray source motion and can safely and conveniently move toany one of a wide variety of positions for standard or other x-rayprotocols and can securely maintain the selected position to take x-rayimages, thus making it possible to use a standard x-ray source in anx-ray room, such as a ceiling-mounted source, with a single digital flatpanel detector for x-ray protocols that might otherwise require pluraldetectors.

One preferred embodiment, described by way of an example and not alimitation on the scope of the invention set forth in the appendedclaims, comprises a detector that is free of a mechanical connectionwith an x-ray source and includes a digital flat panel x-ray detectorarrangement and an anti-scatter grid. A floor-supported base supports anarticulated structure that in turn supports and selectively moves thedetector with at least five degrees of freedom to position it for anyone of a variety of standard or other diagnostic x-ray protocols forstanding, sitting, and recumbent patients. In a non-limiting example,the degrees of freedom include at least two translational and threerotational motions. For example, a first translational motion comprisesmoving a lower slide along the base, a first rotational motion comprisesrotating about a vertical axis a lower arm having a near end mounted onthe lower slide, a second rotational motion comprises rotating aboutanother vertical axis a column mounted at a far end of the lower arm, asecond translational motion comprises moving an upper slide up and downthe column, and a third rotational motion comprises rotating about ahorizontal axis an upper arm having a near end mounted on the upperslide and a far end coupled to the detector. In addition, the detectorcan be rotationally mounted on the far end of the upper arm to rotateabout an axis transverse to its face, for a sixth degree of freedom. Thedetector can also be rocked, i.e. rotated about a vertical axis whenvertically oriented, to provide angulation for cross-table obliqueimaging, as is commonly done for the axiolateral projection of the hip.The more general case is that the detector can be rotated about and axisextending along or generally parallel to its viewing surface.

For certain x-ray protocols, it can be desirable to couple verticalmotion of the detector to vertical motion of a patient table, and suchprovisions are included in the disclosed system. To make moving andpositioning the detector easier, motion in at least some of the degreesof freedom is regulated with detents that bias the motion to preferredsteps and can lock to prevent undesired motion. The motion in one ormore degrees of freedom can be motorized. Further, the motion in some orall of the degrees of freedom can be computer-controlled. A collisionavoidance system can be provided to help prevent pinch-points andcollisions for the motions in one or more of the degrees of freedom.Encoders coupled with moving parts can provide digital informationregarding motion and position, and the information can be used by aprogrammed computer to control the motions in various ways. For example,the information can be used in pinch-point and collision avoidanceand/or in computer-controlling motions that position the detector atselected positions and orientations.

The disclosed system can be used with a patient table on a pedestal thatdrives the table up and down and can move the table along its lengthand, additionally, can pivot the table about a horizontal and/orvertical axis to allow for a greater variety of x-ray protocols. Thesystem can be used without a table, for example for x-ray protocolsinvolving a standing patient or a patient on a bed or gurney orwheelchair. The detector can have a rectangular imaging area, in whichcase provisions can be made for rotating the detector between landscapeand portrait orientations, and further provisions can be made forautomatically detecting the orientation, such as by providing exposuresensors that also serve to provide orientation information. The detectorcan be made with a square imaging area, in which case it need not rotatebetween landscape and portrait orientation, but rotation can still beprovided, for example to image a limb or some other structure along thediagonal of the imaging area, or alternatively to align the anti-scattergrid in a desired orientation. A variant of the disclosed system can bemade for use with a step stool for imaging weight-bearing extremities,where the detector moves with at least two degrees of freedom between ahorizontal orientation under a stool portion on which the patient standsand a vertical orientation alongside that portion of the stool. Anothervariant can be directed to x-ray protocols that do not involve the upperbody of a standing patient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a digital flat panel detector in a verticalorientation, for example for a chest-x-ray of a standing patient, usinga ceiling-mounted x-ray source.

FIG. 2 is a similar illustration, showing the detector at a lowerposition, for example for imaging the legs of a standing patient or fora chest x-ray of a patient on a wheelchair, a gurney or some othersupport.

FIG. 3 is a similar illustration, showing the detector in a horizontalorientation under a patient table.

FIG. 4 is a similar illustration, showing the detector in a horizontalorientation, next to the head of foot of the patient table and at thesame level, for example for imaging a patient's extremity.

FIG. 5 is a similar illustration, showing the detector in a similarhorizontal orientation but next to a side of the patient table, forexample for imaging a patient's arm or hand.

FIG. 6 is a similar illustration, showing the detector also in ahorizontal position but spaced from the table, for example to image thearm of a patient without using the patient table.

FIG. 7 is a similar illustration, showing the detector in a verticalorientation next to a side of the patient table and parallel thereto.

FIG. 8 is a similar illustration, showing the detector in a verticalorientation next to a side of the patent table but angled relative totable side.

FIG. 9 illustrates the detector as used in an x-ray room that has aceiling-mounted x-ray source and further illustrates an operator'sconsole processing the detector output and controlling the x-rayexamination.

FIG. 10 illustrates another embodiments, suitable for x-ray examinationof weight bearing feet or other anatomy.

FIG. 11 illustrates a locking detent used in positioning the detector,with the detent in a position during detector motion.

FIG. 12 illustrates the detent in a locked position.

FIGS. 13-27 illustrate another embodiment.

FIGS. 28-38 illustrate yet another embodiment.

FIGS. 39-41 illustrate a further embodiment.

FIGS. 42-49 illustrate another embodiment.

FIGS. 46-50 illustrate yet another embodiment.

FIGS. 51-53 illustrate a further embodiment.

FIGS. 54-59 illustrate another embodiment.

FIG. 60 illustrates a relationship between an anti-scatter grid andpixels of a flat panel digital x-ray detector.

FIG. 61 illustrates a system for positioning a digital flat paneldetector and a patient table, with the detector under the table, forexample for an AP chest x-ray of a supine patient.

FIG. 61 a illustrates a modification of the system of FIG. 61.

FIG. 62 is a similar illustration, showing the detector in a horizontalposition adjacent a side of the patient table for example for imaging anextremity.

FIG. 63 is a similar illustration, showing the detector in a horizontalposition but adjacent one of the ends of the patient table, for examplefor imaging a patient's head or feet.

FIG. 64 is a similar illustration, showing the detector in a horizontalposition, for example for imaging a patient in a wheelchair.

FIG. 65 is a similar illustration, showing the detector in a verticalposition adjacent a side of the patient table, for example forcross-table lateral imaging.

FIG. 66 is a similar illustration, showing the detector in a verticalposition, for example for a chest x-ray of a standing patient.

FIG. 67 is a similar illustration, showing the detector in a verticalposition as in FIG. 66 but spaced further from the patient table.

FIG. 68 is a similar illustration, showing the detector in a verticalposition close to the floor, for example for imaging a lower extremityof a standing or sitting patient.

FIG. 69 illustrates another embodiment of such system.

FIG. 70 illustrates the embodiments of FIG. 69, with the detector inanother position.

FIG. 71 illustrates another embodiment that is particularly suitable foruse without a permanent patient bed.

FIG. 72 illustrates another embodiment, in which an x-ray source and asupport for a flat panel x-ray detectors are suspended from and can movealong respective tracks mounted above, e.g., at a ceiling.

FIG. 73 illustrates another embodiment, in which a flat panel detectoris mounted in a patient gurney and can be removed from mounting on othersupports.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, a main support 10 can be secured to the floor of anx-ray room (or to a movable platform, not shown), and has a track 12 onwhich a lower slide 14 rides for movement along an x-axis. Slide 14supports the proximal or near end of a generally horizontal lower arm 16through a bearing at 18 allowing rotation of arm 16 about an upwardlyextending axis, e.g., a z-axis. The distal or far end of lower arm 16 inturn supports an upwardly extending, e.g., vertical, column 20, mountedfor rotation about an upwardly extending, e.g, vertical, axis though abearing at 17. Column 20 has a slot 20 a along its length. An upperslide 22 engages slot 20 a to ride along the length of column 20 and issupported by a cable or chain system 24 that reverse direction overpulleys 26 at the top and bottom of column 20 (only the top pulley isillustrated) and connect to counterweights 28 riding inside column 20.Upper slide 22 in turn supports an upper arm 30 through a bearingarrangement at 32 allowing rotation of upper arm 30 about a lateral,e.g., horizontal, axis extending along the length of upper arm 30.Preferably, the bearing arrangement is situated along the center of massof the detector system, which offers a safety feature in case of anaccidental brake or detent release that could turn the detector againstthe patient. Upper arm 30 supports an x-ray detector 34 containing atwo-dimensional digital flat panel detector array, for example of thetype discussed in the U.S. patents cited above, and typically alsocontaining an anti-scatter grid and electronics for receiving controland other signals and sending out digital image and other informationthrough cables (not shown) and/or in a different way. Detector 34 can beconnected to upper arm 30 through a bearing arrangement at 36 (FIG. 7)to allow rotation of detector 34 about an axis normal to the x-rayreceiving face of the flat panel detector. This can be desirable if theimaging area of detector 34 is rectangular, to allow using it inportrait or landscape orientations, or if such rotation is desirable forother reasons, for example to align the detector diagonal with apatient's limb or other anatomy of interest. Alternatively, the bearingarrangement at 36 can be omitted. A handle 38 is attached to detector34, for example when a bearing at 36 is used, or can be attacheddirectly to upper arm 30 otherwise, and has a manual switches or othercontrols at 38 a for control purposes, such as to lock and unlockvarious motions and/or to control motorized movements.

A patient table 40 is supported on a telescoping column 42 that movestable 40 up and down, e.g., along the z-axis, within a guide 44 that canbe floor-mounted, or mounted on a movable support, and may or may not besecured to main support 10. Table 40 is made of a material thatminimizes distortion of the spatial distribution of x-rays passingthrough it. If desired, table 40 can be made movable along the x-axis,in a manner similar to the bed in the QDR-4500 Acclaim systemcommercially available from the assignee of this patent specification,and/or can be made to tilt about one or more lateral axis, e.g., thex-axis and the y-axis, and/or rotate about an upwardly extending axis,e.g., the z-axis. A console and display unit 41 (FIG. 9) can beconnected by cable or otherwise to detector 34 to supply power andcontrol signals thereto and to receive digital image data therefrom (andpossibly other information) for processing and display. The display atunit 41 can be, for example, on a CRT or a flat panel display screenused in the usual manner and image and other information can be suitablyarchived and/or printed as is known in the art. The usual imagemanipulation facilities can be provided at unit 41, for example forlevel and window controls of the displayed digital x-ray image, forimage magnification, zoom, cropping, annotation, etc. The cabling can berun through upper arm 30, column 20, and lower arm 16 to avoidinterference with motion of the articulated support structure betweenmain support 10 and detector 34. Alternatively, detector 34 can bepowered and controlled in some other way, and image data can beextracted therefrom in some other way. For example, detector 34 can be aself-contained detector, with an internal power supply and with controlswitches on or in detector 34 to control its operation. Detector 34 canfurther contain storage for the data of one or more x-ray images. Imagedata can be taken out of detector 34 by way of a wireless connection, orby temporarily plugging in a cable therein when it is time to read imagedata, or in some other way. Detector 34 can include one or more exposuresensors (not illustrated) such as ion chambers used as is known in theart to control x-ray exposure. By arranging five exposure sensors arounddetector 34 such that three would be along the top of the detector for achest x-ray in either orientation of detector 34, and providing amicroswitch or some other sensor (not shown) to detect the orientationof detector 34 and provide a signal directing the use of the threeexposure sensors that at along the top of detector 34 at the time.

Detector 34 typically is used with a ceiling-suspended x-ray source 46of the type commonly present in x-ray rooms. Such x-ray sourcestypically are suspended through telescoping arrangements that allow thesource to be moved vertically and rotated about an axis so the x-raybeam, illustrated schematically at 46 a, can be aligned with an x-rayreceptor such as a film cassette and, in the case of using the systemdisclosed herein, a digital flat panel detector. A translational motionof source 46 may also be possible. Such x-ray sources typically have anoptical arrangement beaming light that indicates where the collimatedx-ray beam will strike when the x-ray tube is energized, and haveappropriate controls for beam collimation and x-ray technique factors.

The first embodiment disclosed herein employs five degrees of freedomfor motion of detector 34, and a sixth degree as well if desired torotate detector 34 about an axis transverse to its plane. Detector 34 isfree of mechanical connection to motions of x-ray source 46, so allmotions of detector 34 are independent of the position or motions of thex-ray source. Further, detector 34 is free of a mechanical connectionwith table 40, so all motions of detector 34 are independent of thepositions or motions of the patient table. However, as explained below,provisions can be made to selectively couple up and down movements ofdetector 34 and table 40 for certain procedures, and provisions can bemade for collision avoidance between the detector 34 and its supportstructure with table 40 and/or x-ray source 46.

A first degree of freedom for detector 34 relates to translationalmotion of slide 14 along main support 10. A second related to rotationof lower arm 16 about the bearing at 18. A third relates to rotation ofcolumn 20 about the bearing at 17. A fourth relates to up/down motion ofupper slide 22 along column 20. A fifth relates to rotation of upper arm30 about the bearing at 32. A sixth degree of freedom, if desired,relates to rotation of detector 34 about the bearing at 36 (FIG. 7).

Through a combination of translating lower slide 14 along base 10 androtating lower arm 16 about the bearing at 18, detector 34 moves alongand across the length of table 40 as desired. The height of detector 34is adjusted by moving slide 22 up or down column 20. The orientation ofdetector 34 is adjusted through rotation about the bearing at 32 and, ifprovided for and desired, through rotation about the bearing at 36.Rotation of column 20 about the bearing at 17 further helps position andorient detector 34.

Patient table 40 and its supporting structure 42 and 44 need not be usedat all for many x-ray protocols and can be omitted altogether fromembodiments of the disclosed system in which detector 34 and itsarticulated support structure are otherwise the same as illustrated inFIGS. 1-9, 11 and 12. As earlier noted, the embodiment illustrated inFIG. 10 does not use a patient table. Patient table 40 can be mountedfor rotation about column 42 through a suitable bearing arrangement (notillustrated), for example though an angle of 90° or more, if desired tomove it out of the way for certain x-ray procedures, or because of theconfiguration of the x-ray room or for other reasons. In addition, oralternatively, table 40 can be mounted for pivoting about a y-axis, forexample an axis at the top of column 42, and/or can be mounted forpivoting about an x-axis, for example at the top of column 42. The table40 could also be mounted for pivoting about a vertical z-axis. Thepivoting can be through any desired angle the mechanical arrangementpermits. Of course, suitable arrangements for locking table 40 inposition can be made.

In the position of detector 34 illustrated in FIG. 1, the x-ray protocolcan be a chest x-ray of a standing patient. For this protocol, slide 14moves to the left in the drawing, lower arm 16 rotates to point awayfrom base 10, column 20 rotates to point upper arm normal to base 10 andlower arm 16, and upper arm 30 rotates to orient detector 34 vertically,facing x-ray source 46 that has been, or is, moved to a suitableposition so that its optical arrangement shows proper alignment withdetector 34. The vertical position of detector 34 is adjusted by slidingupper slide 22 along column 20. If detector 34 has portrait andlandscape orientation, it is rotated to the desired orientation, and anx-ray exposure is taken after setting the x-ray technique factors andpositioning a patient as in known in the art. In an embodiment employingmanual movement, the operator pushes appropriate buttons 38 a on handle38 to release the articulated structure between detector 34 and base 10for the appropriate movement, and pushes or releases appropriate buttonsat the end of the movement to lock the structure in place for the x-rayprocedure. A single button or other operator interface can be used torelease all parts of the articulated structure for movement and to lockthem for an x-ray procedure, or respective buttons of other interfacedevices can be used for individual movements of combinations of lessthan all movements. If some or all of the movements are motorized, theoperator uses suitable buttons or other controls to unlock the movementsand direct the motorized motions and then lock the articulated structurein position.

If greater distance between detector 34 and table 40 is desired, lowerarm 16 is rotated to be transverse to base 10, e.g., perpendicular tobase 10, and column 20 is rotated to keep upper arm 30 pointing as shownin FIG. 1. In addition, table 40 can be moved all the way to the rightin FIG. 1 along is permitted x-axis motion, and/or can be rotated ortilted as earlier described.

The position illustrated in FIG. 2 can be used for a protocol such asimaging the leg or legs of a standing patient, or imaging a patient on awheelchair or a gurney. It is similar to the position FIG. 1illustrates, and detector 34 can be moved thereto similarly, except to alower vertical position. Again, if greater distance from the side oftable 40 is desired, lower arm 16 can be angled transverse to the lengthof base 10. X-ray source 46 is not shown in FIG. 2 but is in a positionto direct the x-ray beam at detector 34 through the patient.

FIG. 3 illustrates a position suitable for example for a chest AP imageof a recumbent patient, e.g., in the supine position on table 40. Table40 can be lowered to make it easier for the patient to get on and thenraised if desired. For this x-ray protocol, detector 34 is moved to ahorizontal orientation below patient table 40 by moving the articulatedsupport structure as earlier described. If desired, detector 34 andtable 40 can be interlocked when in the illustrated positions, tothereafter move up or down as a unit. The interlock can be mechanical,by a clamp or pin (not shown) in case upper slide 30 is moved manuallyalong column 20, so that detector 34 would be driven vertically bymotorized vertical motion of table 40. If slide 30 is motorized, thevertical motion of slide 30 and table 40 can be synchronized throughknown electronic controls. Table 40 is moved all the way to the left asseen in FIG. 3 in this example.

FIG. 4 illustrates a position in which detector 34 is also in ahorizontal orientation and faces up, but is at the head or foot of table40 and substantially coplanar therewith. X-ray protocols such as imaginga limb or the head of a patient recumbent on table 40 can be carried outin this position of detector 34 and table 40. Table 40 is moved to theright as seen in FIG. 4 in this example. X-ray source 46 is not shown inFIG. 4 but would be above detector 34.

FIG. 5 illustrates a position of detector 34 and table 40 suitable forx-ray protocols such as imaging an arm or a hand of a patient recumbenton table 40. For this protocol, detector 34 is moved to one side oftable 40, in a horizontal orientation and facing up. Detector 34 can becoplanar with table 40 or can be vertically offset therefrom by aselected distance. The disclosed system allows detector 34 to be movedto either side of table 40 and to be at any one of a number of positionsalong a side of table 40 and to be spaced from table 40 both laterallyand vertically by selected distances. X-ray source 46 is not shown inFIG. 5 but would be above detector 34.

FIG. 6 illustrates a position of detector 34 suitable for a protocolsuch as imaging an arm or a hand of patient who can be on a wheelchair,a gurney, or can be standing. The positioning in FIG. 6 is similar tothat in FIG. 1 except that detector 34 is lower vertically and isoriented horizontally and facing up. X-ray source 46 again is not shownin FIG. 6 but would be above detector 34.

FIG. 7 illustrates a position of detector 34 suitable for x-rayprotocols such as a cross-table lateral view of a patient recumbent orsitting on table 40. For this protocol, detector 34 is orientedvertically, facing a side of table 40. Typically, the lower edge of theimage area of detector 34 is at or higher than table 40. X-ray source 46in this case would be at the other side of table 40, with its x-ray beamdirected horizontally at detector 34.

FIG. 8 illustrates detector 34 in a position similar to that in FIG. 7,also in a vertical orientation but angled relative to a side edge oftable 40, through rotation of lower arm 16 and/or of column 20. X-raysource 46 would be across table 40 from detector 34, typically with thecentral ray of the x-ray beam normal to the imaging surface of detector34.

FIG. 9 illustrates detector 34 in a position similar to that in FIG. 1but shows more of the structure suspending x-ray source 46 from theceiling, and illustrates a console 41 coupled electrically andelectronically with detector 34 and, if desired, with x-ray source 46and placed behind a known x-ray protection screen.

FIG. 10 illustrates an embodiment that can use only two degrees offreedom for detector 34 and is suitable for x-ray protocols such asimaging patients' feet when weight-bearing. Column 50 in this embodimentis similar to the earlier-described column 20, except that column 50need not be on a lower arm 16 but can be on a support 52 that can befloor-mounted or can be mounted on a movable platform. Column 50 isrotatably mounted on support 52 through a bearing at 54, to rotate aboutan upwardly extending axis such as its long axis. An arm 56 is mountedon a slide 58 that moves along column 50, for example through achain-and-pulley arrangement 60 counter-weighted with a weight 62. Arm56 is mounted on slide 58 through a bearing at 57 to rotate about alateral, e.g., horizontal, axis. In use, a patient climbs on steps 64,holding onto a floor or wall mounted handrail 66 if desired, and standson a low platform 68 that is essentially transparent to x-rays. Detector34 can be positioned as illustrated, in a horizontal orientation underplatform 68, facing up. X-ray source 46 would be above the patient'sfeet, with the x-ray beam directed down toward detector 34. By graspinga handle 69, an operator can pull detector 34 from under platform 68 byrotating column 50 through arm 56, and can then rotate arm 56 aboutbearing 57 to move detector 34 to a vertical orientation adjacent to andaligned or above platform 60 for an x-ray protocol calling for a lateralimage of the patient's feet. An assembled unit comprising steps 64,platform 68 and a handrail 66 secured thereto can be on wheels 71 sothat it can be moved as needed.

FIGS. 11 and 12 illustrate a locking detent mechanism that can be usedfor one or more of the rotational motions described above. In acurrently preferred embodiment, such a detent is used for the rotationof lower arm 16, column 20 and upper arm 30, and can be used forrotation of detector 34 about bearing 36 (FIG. 7). A similar detent canbe used for the rotation of column 50 and arm 56 in the embodiment ofFIG. 10. Taking as a representative example the rotation of lower arm 16about lower slide 14, and referring to FIGS. 11 and 12, a plate 100 issecured to, or is a part of the non-rotating element, in this exampleslide 14, and a cogwheel 70, or a segment of such a cogwheel is securedto the rotating part, in this example lower arm 16. Cogwheel 70 has apattern of valleys 70 a and teeth 70 b. A cam wheel 72 is mounted forfree rotation on a lever 74, which in turn is pivotally mounted on plate100 at a pivot 76 and is biased toward cogwheel 70 by a spring 77 (FIG.12). When lower arm 16 is urged into rotation with a force sufficient toovercome the bias of spring 77, as well as inertial and friction,camwheel 72 rides over the teeth of cogwheel 70 but when the forcerotating lower arm 16 is below a threshold, the mechanism forcescamwheel 72 into a valley 70 a, so that the rotation of lower arm 16stops at one of the several preferred positions, spaced approximately15° apart in a currently preferred embodiment. When lower arm 16 is in adesired position, the detent mechanism is locked by releasing a solenoid78 to allow its spring to force lever 80 to its position illustrated inFIG. 12, in which it comes under the right side of lever 74 to keepcamwheel 72 in a valley and thus prevent rotation of lower arm 16. Toallow rotation of arm 16, solenoid 78 must be energized to pull lever 80to the position thereof illustrated in FIG. 11, which can be done, forexample, by operation of a control button 38 a on handle 38 in the caseof the embodiment of FIGS. 1-9 or similar button 38′a on handle 38′ inthe embodiment of FIG. 10. While identical types of detents can be usedfor each rotational motion, a different arrangement of cogwheel teethmay be desired. For example, rotation about bearing 36 may require onlytwo or three preferred positions C portrait, landscape and diagonalorientations C in which case the cogwheel may need only three valleysbetween teeth. Other rotations may require a different angular range, inwhich case the segment of cogwheel 70 that is used may have a differentinclusion angle.

Alternatively, electronic, electromechanical and/or mechanical brakesand clutches can be used to immobilize and release the connectionsbetween parts that can move relative to each other. Using such brakesand clutches can allow the operator to move detector 34 to the desiredposition manually with ease, and can securely fix detector 34 in aposition for exposure. For example, the operator can trip switch 38 a toengage such clutch or clutches and/or brake or brakes to thereby allowmotion, and can trip the switch to disengage such clutch(es) and/orbrake(s) to thereby prevent motion. Such a clutch and/or brakearrangement can be used for one or more of the motions described above.Separate such arrangements can be used for different ones of themotions.

Instead of manually moving detector 34 to the desired position asdescribed above, respective electric or other motors can be used todrive some or all of the motions discussed above, under operatorcontrol. Alternatively, some or all of the motions can be automated, sothat the operator can select one of several preset motion sequences, orcan select vertical, horizontal and angular positions for detector 34,and computer controls can provide the necessary motor control commands.Particularly when movements are power-driven rather than manual,proximity and/or impact sensors can be used at the moving parts as asafety measure, generating stop-motion signals when a moving part getstoo close to, or impacts with, an object or a patient.

Detector 34 can contain a flat panel detector that converts x-raysdirectly into electrical signals representing the x-ray image, using adetection layer containing selenium, silicon or lead oxide.Alternatively, detector 34 can contain a flat panel detector that uses ascintillating material layer on which the x-rays impinge to generate alight pattern and an array of devices responsive to the light pattern togenerate electrical signals representing the x-ray image.

The disclosed system can be used for tomosynthesis motion, where thex-ray source and the detector move relative to each other and thepatient, or at least one of the source and detector moves, either in acontinuous motion or in a step-and-shoot manner. The image informationacquired at each step (or each time increment) can be read out and thedetector reset for an image at the next step (or time increment). Analternative method of performing tomosynthesis can be used where thesource and detector motions relative to the patient occur as describedabove, but only one image is generated from the entire motion sequence,representing a composite image acquired over all the positions.

The disclosed system provides for a number of motions to accommodate awide variety of imaging protocols: the x-ray detector image planerotates between vertical and horizontal and can be locked atintermediate angles as well; the detector moves horizontally along thelength of the patient table as well as across the length of the patienttable so that it can be positioned at either side of the table; thedetector moves vertically, the detector can move between portrait andlandscape orientations for non-square detector arrays and/or for desiredorientation of the array grid even for square arrays; and the detectorcan combine some or all of these motions in order to get to any desiredposition and orientation.

Safety can be enhanced by moving the detector by hand, so the operatorcan observe all motion and ensure safety. Sensors can be provided forcollision detection when any motion is motorized. When any motion ismotorized, easy-stall motors can be used to enhance safety. In addition,when any motion is motorized, encoders can be provided to keep track ofthe positions of moving components, and the encoder outputs can be usedfor software tracking and collision avoidance control. When motions aremotorized, preset motor controls can be stored in a computer and used todrive the detector motion for specified imaging protocols or detectorpositions so that the detector can automatically move to a presetposition for a given imaging protocol. Undesirable motion can be avoidedor reduced by using clutch controls, hand brakes, counter-balancing,and/or detents that help identify and maintain a desired detectorposition and orientation and help prevent grid oscillation and focusinggrid misalignment.

FIGS. 13 through 27 illustrate another embodiment. The articulatedstructure supporting detector 34 in this embodiment comprises a mainsupport 102 (FIGS. 26 and 27) that typically is floor-mounted but can bemounted on a moving platform or on some other support such as a wall. Atelescoping sleeve 104 rides up and down on support 102. A column 106 ispivotally mounted on sleeve 104 to pivot about a horizontal axis, and anarm 108 is pivotally mounted on column 106 to ride along its length andto pivot about a horizontal axis. A support 110 extends from arm 108 andanother arm 112 is pivotally secured to support 110 at a pivot axis 114(FIG. 27). Detector 34 is secured to the other end of arm 112, to pivotabout an axis 116 normal to the detector's imaging surface. Suitablebrakes, clutches, locks, detents and/or counterweights are provided tofacilitate positioning detector 34 for a multiplicity of x-rayprotocols, either by moving some or all of the articulated structure byhand or by motorizing some or all of the motions. Some of the positionsof detector 34 are illustrated in FIGS. 13-27 but it should be apparentthat many more positions are possible with this articulated supportarrangement. A patient table 120 (FIGS. 13-15) is mounted on twocross-members 122, 124 supported on respective sleeves 126, 128 that cantelescope up and down on respective main supports 130, 132. In thismanner, table 120 can move up and down (see difference between FIGS. 14and 15) and can tilt, e.g. to move out of the way for a chest x-ray of astanding patient (see difference between FIGS. 13 and 14). Thisembodiment can thus be used with or without the patient table and itssupports, for a multiplicity of x-ray protocols for standing, sitting orrecumbent patients.

Yet another embodiment is illustrated in FIGS. 28-37. In thisembodiment, the articulated structure supporting detector 34 comprises amain support 150 mounted on rails 152 for motion along the rails towardand away from patient table 154. A vertically telescoping column,generally illustrated at 156, moves up and down an arm 158 having oneend mounted thereon for rotation about the vertical central axis ofcolumn 156. Detector 34 is mounted at the other end of arm 158 to rotateat least about an axis parallel to its imaging surface, so that detector34 can rotate between horizontal and vertical orientations (compareFIGS. 28 and 29). Preferably, detector 34 is mounted on arm 158 forrotation about an additional axis as well, normal to the imagingsurface, for changing between portrait and landscape orientations or forother purposes. In this embodiment, patient table 154 is mounted on atelescoping support generally illustrated at 160. Table 154 moves up anddown by the telescoping motion of column 160 (compare FIGS. 32 and 33),and rotates about a vertical axis (compare FIGS. 28 and 29). Inaddition, arm 158 can be made to telescope (FIGS. 36-38) to furtherfacilitate the positioning of detector 34 for different x-ray protocolsfor standing, sitting and recumbent patients. Only some of thesepositions are illustrated in FIGS. 28-38, for use with an independentlymounted x-ray source.

As illustrated in FIGS. 39-41, the articulated support for detector 34can be used for x-ray protocols that do not call for a patient tablesuch as table 154. In FIGS. 39-41, a gurney 162 supports the patientsand is wheeled to the support for detector 34 that can be on rails 152.Detector 34 in this embodiment can be positioned as illustrated in FIGS.39-42 or in other positions, some of which are illustrated in connectionwith FIGS. 28-38, for a multiplicity of standard x-ray protocols.

Yet another embodiment is illustrated in FIGS. 42-45. In thisembodiment, detector 34 is mounted for motion along and across rails 166that are mounted on a support 168 and pivot about a horizontal axis at169, between a horizontal and vertical orientations of detector 34(compare FIGS. 42 and 43). Patient table 170 is mounted on a support 172to pivot about an axis parallel to axis 169, at least between thepositions illustrated in FIGS. 42 and 43. Detector 34 can slide acrossthe length of rails 166, between the positions illustrated in FIGS. 44and 45, on another set of rails (not shown). In this manner, detector 34can be used for a variety of protocols, including but not limited tox-rays of a standing patient or a patient on a wheelchair (FIG. 43), apatient recumbent on table 170 (with detector 34 under the table), andfor a body part extending to the side of table 170 (FIG. 45).

Another embodiment for positioning detector 34 relative to a patient bedis illustrated in FIGS. 46-50. In this embodiment, detector 34 issecured to a patient platform 180 mounted at 182 for pivoting about ahorizontal axis at least between the positions of FIGS. 48 and 49. Acounterweight 184 facilitates the pivoting motion. Detector 34 issecured to platform 180 through rails (not shown) extending along thelength of the platform, and rails (not shown) extending across thelength of the platform, for sliding motion along each set of rails. Inthis manner, detector 34 can slide along the length of platform, underthe platform so a patient recumbent on the platform can be x-rayed withan independently supported x-ray source, such as ceiling-supportedsource. In addition, detector 34 can slide across the length of platform180 so it clears the platform (in top plan view) and in that positioncan pivot about an axis at its edge closer to the platform to assume avertical orientation, e.g. as illustrated in FIG. 46. In the uprightposition of patient platform 180, the patient can stand on a support 185that can be made to move up and down the upright platform 180, forexample by motorizing the motion. While detector 34 is not illustratedin FIGS. 48 and 49, it should be apparent that it is at the side ofplatform opposite the patient.

Detector 34 can be on a rolling articulated support structure, asillustrated in FIGS. 51-53. In this embodiment, a wheeled platform 200supports a vertical column 202 that in turn supports an arm 204 movableup and down column 202 (compare FIGS. 51 and 52) and pivoting about ahorizontal axis (compare FIGS. 52 and 53). The rolling structure can beused with a patient bed 206 that can move up and down on its telescopingsupport 208 (compare FIGS. 51 and 52) and along its length (seedifferent positions of bed 206 illustrated in FIG. 52). The detectorsupport structure can be used without a patient bed, for example for achest x-ray of a standing patient, as illustrated in FIG. 53, or for anumber of other x-ray protocols. A standard x-ray source 46 can be used.

In yet another embodiment, illustrated in FIGS. 54-59, detector 34 canbe supported on structure generally indicated at 250 that in turn issupported for sliding motion along the length of a patient table 252(compare FIGS. 54 and 55) and for rotation about a horizontal axistransverse to the length of table 252 (compare FIGS. 54 and 55 a). Table252 is in turn mounted on a vertically telescoping pedestal 254 that ison a rolling platform 256. As seen in FIG. 56, detector 34 is mounted onan arm 258 articulated at 260 for rotation about an axis normal to theimaging surface of detector 34 to allow the detector to move between thetwo illustrated positions, one under patient table 252 and one to theside of the patient table. In addition, as seen in FIG. 57, arm 258 canrotate about an axis 262 parallel to one of its sides, to a verticalorientation, and can slide along the length of support 250 to positiondetector at different points along the length of patient table 252.FIGS. 58 and 59 illustrate the mounting of arm 258 for rotation aboutthe two axis of interest. In addition, detector 34 can be mounted on arm250 for rotation between portrait and landscape orientations.

The system as described can be enhanced in a variety of other ways toimprove functionality and to take advantage of the flexibility of thedigital image generation.

When using x-ray film, the sharpest images typically occur when thepatient is positioned as close as practical to the film. This protocolalso avoids object magnification and the film has a 1:1 image and sogeometric distances can be easily measured. In a digital image, there isno requirement that the image be 1:1 to the object. Display monitorscome in a variety of sizes. In a digital image, the pixel size in theobject plane can be calculated, and distances on the image can be thuscalibrated. In addition, the optimum object-imaging detector distance(OID) for a digital detector is different than that for film. For film,the OID that maximizes object sharpness in the object plane is 0, i.e.the object plane is as close to the film as practical. In a digitaldetector, the optimum distance can be where the combined effectivesystem resolution, in the object plane, due to the focal spot blur andthe pixel size is a minima. This occurs for non-zero OID, and in a flatpanel system with a pixel size of 139 microns and a x-ray tube focalspot size of 0.5 mm, the optimum OID is roughly 7 cm.

The calibration of the pixel size in the object plane depends on themagnification factor, which is a function of both the source-imagingdetector distance (SID) and the OID. Once the magnification factor isdetermined, the effective pixel size is known, and the magnificationfactor [M=SID/(SID-OID)] and/or pixel size can be inserted into thepatient record, for example in the appropriate fields in the DICOMheader. The display workstation software can use or display theinformation to establish a metric for the pixel size. Alternatively, theimage could be remapped into one where the pixel size had amagnification factor of 1; this is useful in situations where the imageis printed on hardcopy and manual measuring means are used. Thedetermination of the magnification factor requires knowing the SID andthe OID. One method is to measure the SID and OID. In one embodiment ofthis, encoders or sensors (not illustrated) can determine the SID andOID. In another embodiment, the SID and OID can be inferred from theacquisition protocol, for example in a standing chest image, the SIDmight be known to be 72 inches. In yet another embodiment, imageprocessing of the acquired image might allow the determination of themagnification factor, such as though the measurement of a known fiducialphantom in the field of view, or through direct analysis of the acquiredimage.

The acquisition parameters such as x-ray tube voltage kVp and power mAsand knowledge of the SID and/or OID can be used to estimate the patiententrance dose. In a preferred embodiment of the system, this doseinformation is inserted into the patient record or DICOM header.

The fact that in a digital flat plate system the optimum OID is non-zeroimplies that means to keep the object being imaged at the optimum OID isa useful addition to a digital radiographic system. One embodiment ofthis would be a radiolucent frame (not shown in the drawings) thatprevents the patient from being imaged closer than some predetermineddistance.

Because the detector 34 can be positioned vertically independently ofthe patient bed's vertical position, a situation where the detector ispositioned under the bed allows the possibility that the detector mighterroneously be a considerable distance under the bed. This could happenif the bed were raised without raising the detector through acorresponding vertical distance. Thus, a system to prevent or alert theoperator to this improper situation would be useful. In one embodimentof this, an encoder or sensor (not shown) determines the distance fromthe detector to the bed. This distance determination can be used toautomatically move the detector into the desired distance from the bed,or alert the operator of the improper position so as to avoidunnecessary exposure, or prevent exposure through an interlock until thedetector is properly positioned. In another embodiment, the detectormechanically locks into the bed frame, so it would move vertically alongwith the patient bed.

As described in one preferred embodiment, the detector can be rotatedfrom portrait to landscape orientation, especially useful for non-squarepanels, or rotated by 45° or some other angle to align the diagonal ofthe panel to a long object being imaged. In situations where thedetector can be rotated, it is useful for the control system to know theorientation of the panel. This allows the determination of up and down,left and right on the image. One method of determining the detectororientation is through the use of encoders or sensors (not shown in thefigures) that measure the detector orientation, and transmit thisinformation into the control system. Once determined, this informationcan be used in a variety of ways. The orientation information can beinserted in the patient record or DICOM header file on the coordinatesystem of the acquired image. This information could be printed on theimage itself. This information can also be used to control the automaticcollimation of the x-ray source, to minimize radiation exposure to thepatient areas not imaged on the detector. This information canadditionally be used to reorient the image into a standard displayformat. For example, if an image of a hand was acquired with the bonesof the fingers aligned horizontally, but the radiologists preferredseeing hand images with fingers aligned vertically, the software candetermine from the detector orientation that the image needed to berotated by 90° before storage or display.

In a variant of the above that does not require the measurement of thedetector orientation, the image can be computer-analyzed and theorientation of the imaged body part determined through image processingmeans. The image can then be rotated before storage or display topresent the body part in a standard orientation.

The determination of the orientation of the detector relative to thex-ray source is useful for other reasons. X-ray sources have an emissionpattern that is non-uniform. In particular, the so-called heel effectcauses the energy and flux to vary depending upon the relative angle ofthe detector to the anode. In film-screen imaging, the anode ispositioned relative to the body so as to minimize this effect—thehigh-output side of the x-ray tube is positioned over the thicker bodyparts, if possible, so as to produce a more uniform illumination on thefilm. In a digital image, the heel effect can be corrected. In oneembodiment of this, the orientation of the detector relative to thex-ray source is used to correct the acquired image for thenon-uniformity due to the heel effect. The heel effect non-uniformitycan be calculated, measured in previous calibration procedures, orestimated from the image using image-processing means.

The use of an anti-scatter grid is another reason to measure theorientation of the detector and anti-scatter grid relative to the x-raysource. Anti-scatter grids are often made of thin strips (laminae) ofradio-opaque material, such as lead separated by more-or-lessradiolucent spacer materials. These grids often shadow the detector witha non-uniform absorption of the incident radiation, causing imagenon-uniformity. This non-uniformity often has a geometrical orientationto it, and may be more pronounced along a given axis. The intensity ofthe non-uniformity is also dependent upon the SID. In a preferredembodiment of the system, the image can be corrected to undo the effectof the modulation non-uniformity. In one embodiment of the correctionmethod, the system uses sensors to determine the orientation of the gridrelative to the detector. This information is used, along with a modelof the grid behavior, to estimate the effect of the grid on the acquiredimage and to eliminate it. Sensors or other means of measuring the SIDare used to change the intensity of the non-uniformity correction. Ifthe grid can be removed from the system, microswitches or other sensormeans can be used to disable the grid cutoff correction if theanti-scatter grid is not present, and enable it when the grid ispresent.

Another embodiment of the anti-scatter grid correction method involvesseparate previously-performed calibrations of the anti-scatter grid'seffect on image non-uniformity. These calibrations can involve imagingthe detector with the anti-scatter grid in various orientations and atdifferent SID and storing these calibration tables for use in thecorrection algorithm. Depending on the presence and orientation of theanti-scatter grid to the detector, and the orientation and distance ofthe x-ray source to the detector and grid assembly, the appropriatecalibration table can be accessed and used to correct the image.

In another embodiment of the invention, sensor means determine not onlythe presence and orientation of the anti-scatter grid, but alsodetermine the type of grid installed. This is useful for installationswhere different types of anti-scatter grids are employed. The imagecorrection methods can correct for the characteristics of the specificgrid employed.

The sensor signal indicating the presence or absence of the anti-scattergrid can also be used to alert the user, or prevent x-ray exposure, insituations where the protocol specifies the use or absence of a grid,and the system determines that the actual grid status is in conflictwith the desired grid status.

Still another embodiment of the anti-scatter grid correction methodinvolves an image processing means. Computer analysis of the image canbe used to extract out the slowly-varying non-uniformity caused by theanti-scatter grid and to correct for it. The heel effect can be analyzedand corrected similarly.

The anti-scatter grid and the detector do not have to maintain aspecified orientation relative to each other. There are situations wherethe grid would be preferentially rotated 90° or other angle relative tothe detector, to allow independent alignment of the grid and detector.The system as described in this patent specification can allow thispossibility. Sensors, encoders, or switches can be used to measure theseparameters, and the system can utilize this information for control andcorrection means.

Under certain imaging protocols, the detector and x-ray source aretilted relative to each other, so that the central axis of the x-raysource is not normal to the surface of the detector. If the anti-scattergrid's laminae are not properly oriented with respect to the x-raysource, well-known imaging artifacts and severe grid cutoffs can occurin the acquired image. This can render the image unusable, and thepatient is exposed to radiation for no positive purpose. The abovedescribed sensors and measuring means to determine the presence orabsence of the anti-scatter grid, and the grid's orientation relative tothe x-ray source can be used by the control system to determine if thedetector is improperly oriented. In this case, the x-ray exposure can beprevented using interlock means, or a warning can be presented to theoperator.

In another preferred embodiment, the x-ray source can be moved into thecorrect orientation and SID relative to the detector, depending upon theprotocol chosen by the operator. The detector is moved by hand to thedesired location. The position and orientation of the detector aredetermined by sensor or encoder means, and then with motors and encodermeans the x-ray source is moved to the corresponding correct locationrelative to the detector. In another embodiment, both the x-ray sourceand the detector move automatically under motor control to the correctpositions for the procedure, which was previously selected by theoperator. Sufficient collision avoidance and collision detectionmechanisms provide safety for personnel and for equipment.

The position and orientation of the x-ray source and detector can bedetermined through any of a number of well-known encoder and sensortechnologies. One specific sensor embodiment that is particularlyattractive can use wireless RF or electromagnetic tracking anddigitizing systems, such as currently manufactured by PolhemusCorporation or Ascension Technology Corporation. These systems measurethe position and orientation of sensors with 6 degrees of freedom.

Anti-scatter grids are often employed in radiographic imaging to reducethe image-degrading character of scattered radiation on the image.Stationary anti-scatter grids can cause well-known moiré patternartifacts that are especially troublesome in a digital detector. Severalembodiments of the system disclosed in this patent specification providefor the reduction or correction of moiré patterns. One embodimentemploys a mechanical means to reciprocate or move the grid relative tothe detector, during the exposure, to blur out the moiré pattern. Thisrequires synchronizing the grid motion to the exposure signal.Reciprocating grid assemblies can be expensive, and can cause unwantedvibration, so methods of reducing the moire pattern without grid motionare especially attractive. One embodiment for stationary grids employsimage processing means to remove the periodic pattern caused by thebeating of the spatial frequency of the scatter grid with the spatialfrequency of the pixel size repetition. This algorithm can utilize thegrid sensors previously described to determine the type of gridemployed, and its orientation relative to the detector.

Other embodiments reduce the moiré pattern through selective design ofthe anti-scatter grid. It is known, for example, that moiré patterns donot occur or are suppressed in a system where the detector pixel pitchhas a period exactly 1:1 (or an integral multiple thereof) to the periodof the anti-scatter grid pitch. One difficulty with such a design isthat it is requires the manufacture of a grid with extremely precisedimensions, otherwise a pattern will likely still occur. Anti-scattergrids are composed of alternating laminae and spacers, and differentbatches of spacers or laminae, for example, might have slightlydifferent dimensions. If an anti-scatter grid is manufactured with aperiod P slightly smaller than the detector pixel pitch D (D=P+ε, whereε is small compared to P), then the reduction of moiré pattern willoccur when this grid is mounted a small distance above the detectorfront surface, the optimal distance depending upon the relativedimensions of the pixel periodicity and the grid periodicity. This moirépattern reduction would also work for grids and detector periods havingrelationship D=NP+ε, with N an integer. In another preferred embodiment,the detector housing can allow the mechanical mounting of the grid asmall, but adjustable, distance above the plate. See FIG. 60 for aschematic illustrating this. During system calibration, the optimumdistance is determined, and the mounting mechanism adjusted via shims orother means to position the grid the correct distance from the plate.Such a system can have a greater insensitivity to manufacturingtolerances of the grid and detector pixels.

FIG. 60 illustrates a focusing anti-scatter grid. In these grids, thepitch of the septa is different on the detector face relative to theobject face. For these grids the relevant grid pitch that determines themoiré pattern is the pitch of the grid septa facing the detector.

Other system embodiments are desired or useful in a digital system. Onepreferred embodiment includes the capability of the system to perform alow-dose preview image prior to the final full-radiation image. In thisprocedure, the patient is positioned as desired, and a low-dose scoutshot is performed. The resultant image is displayed, and is analyzed bythe operator for proper positioning of the patient, detector, and x-raytube. If the alignment is adequate, a second full-exposure image isacquired.

In some procedures the patient can cradle the image receptor, as withfilm. An example of this is a standing chest AP image, where the patientwould desirably cradle his arms around the detector. Often the patientwill also support his weight partially with the detector. To facilitatethis, a preferred embodiment of the system will include handles on thedetector housing, for patient gripping. If there are controls on thedetector housing that could be touched by a patient, it is desirable tobe able to disable these controls to prevent accidental engagement bythe patient. For standing chest imaging where the patient is supportinghis weight partly on the detector, sufficient braking resistance can beprovided to prevent accidental detector motion. Imaging protocols on thebed can also benefit from patient handholds. An example would be imagestaken where the patient is standing on the bed. In some of the proposedembodiments, there is a vertical column that supports the detector, andpatient handholds on this column can be useful for the above mentionedpatient support reasons. Another use of the vertical column can be as asupport stand for a display screen, useful for operator control use.

Another important design criteria for the system is to protect thedetector from accidental entry of body fluids, blood, and other liquidsthat might be spilled. The entry of these liquids into sensitiveelectronics might be harmful to the system, and can present a cleaningchallenge. In one preferred embodiment, the detector housing is designedfor easy cleaning, such as with a flat front surface. The seam for theopening of the detector housing could be in the rear of the housing,away from the front surface. The flat front surface is easily cleaned,and the rearward mounted seam would be less likely to introduce liquidentry into the detector. The seam could be sealed with an o-ring tofurther discourage liquids. Simple draping of the detector housing inplastic might not be desirable, as it might interfere with cooling fansneeded for the electronics. Practical designs for the detector housingshould account for the heat generated by the electronics associated withthe flat panel detector. Analog-digital converters, amplifiers, andother components often have undesirable temperature coefficients, andtherefore the flat panel is optimally maintained at a given temperature.Thus, in a preferred embodiment, the detector housing can have means tomaintain a stable temperature, or at least prevent the temperature fromexceeding certain limits.

Other advantages of the digital flat panel arise from the digital natureof the image. In one preferred embodiment, the controlling computersystem automatically keeps a log of system and operator performance. Thesystem measures and stores a history of each exposure and its associatedparameters, such as: exposure time, x-ray tube current and kV,source-detector and source-patient distances. The system also keeps arecord of image retakes and the type of imaging protocol used. Thisdatabase can be used to evaluate system and operator performance. Inanother embodiment, the system performs automatic quality control andcalibration. For safety reasons, x-ray tube outputs need to be verifiedroutinely by in-hospital physicists. This can prevent dangerousirradiation of patients by faulty equipment. A film system offers usefulwarning on x-ray malfunction, because the operator will notice that thefilm exposures are not optimal. A digital system has a greater dynamicrange, and will tolerate a larger variation in x-ray output before aproblem is noticed by image degradation. Therefore, a useful check ofsystem performance is an algorithm that determines if the recorded imageis in concert with the expected image based on tube voltage andcurrents. This analysis can be performed on images taken in a specialquality control procedure, or on the routine patient images. Feedback tothe user is provided when the system indicates a possible problem.Another preferred embodiment for quality control is a system thatemploys automated procedures that verify that the stored calibrationfiles, such as pixel gain and offset, and bad pixel maps, are correct.This can include the system making exposures and testing the uniformityof a flood field. These calibrations can proceed essentially withoutuser intervention, and can be performed on a routine basisautomatically. In another preferred embodiment, the system can becontrolled and accessed remotely, such as through a modem or networklink, so that system debugging and maintenance can be offered by aservice organization and provide faster service response withoutrequiring a field service visit. In this system, the remote user wouldbe able to access and analyze image and calibration files, and controlthe system to perform automatic tests.

In the system, the operator will control the exposure time and voltage,and determine the correct SID for the procedure, by selecting thedesired protocol from a list containing the most commonly performedprotocols. There are literally hundreds of possible protocols, and aconvenient method of quickly accessing the desired one is useful. In apreferred embodiment, the set of acquisition protocols can be organizedin a hierarchical folder arrangement. The hierarchy is most convenientlyorganized by body parts, with each lower level containing a list of moreand more specific body regions. For example, the protocol AP Oblique ofthe Toes, is accessed through a folder selection like the following:

-   1. Lower limbs-   2. Feet-   3. Toes-   4. AP Oblique.    Information on the acquisition protocol can also be automatically    inserted into the patient record or DICOM header of the image file.

Currently, digital images have a greater dynamic range than that of thedisplay device, and the image typically is processed before display tooptimize its performance. The image contains areas of greatly varyingx-ray exposure, from areas with little exposure directly under anattenuating body area to areas exposed to the direct x-ray beam withvery large exposure. Preferably, the system will determine the locationof the area of interest, and will adjust and map the image into one thatoptimizes the display of that area. In one preferred embodiment, theoperator will indicate on the image the approximate region of thedesired area for analysis, and the display will then be optimized to theexposure in that region. This system can take the form of amouse-controlled cursor, which is used to click on or outline orotherwise define the area. In another preferred embodiment, the computercan use the knowledge of the protocol being employed and perform imageanalysis to locate the body part of interest and optimize the display ofsaid part. For example, in an AP chest image, the display might optimizethe display of the lungs, spine, or other organ depending on the imageprotocol. Preferably, information on the mapping transformation isstored or else both the original image and the remapped image arestored, so that the image can be reverted to the original or remappedwith different parameters if so desired by the operator.

Yet another preferred embodiment refers to a convenient method for theoperator to access the patient images that have been performed.Commonly, just a text listing of the studies is displayed on a computerscreen, and the operator must read through the list to choose thedesired images for display or transfer or storage. In this preferredsystem, a thumbnail image of the study is displayed next to the textualinformation. This provides a visual cue to the operator, facilitatingthe selection of the correct files.

Referring to FIG. 61, a main support 6110 can be secured to the floor ofa radiology room (or to a movable platform, not shown), and has a track6112 (see FIG. 66) on which a horizontal slide 6114 rides for movementalong an x-axis. Slide 6114 supports a generally horizontal lower arm6116 through a bearing 6118 allowing rotation of arm 6116 about az-axis. The distal end of arm 6116 in turn supports a column 6120extending along the z-axis and having a vertical slot 6120 a. A verticalslide 6122 (see FIG. 65) engages slot 6120 a for vertical movement alongthe height of column 6120 and is supported by cables 6124 that reversedirection over pulleys 6126 and connect to counterweights 6128 ridingvertically inside column 6120. Vertical slide 6122 in turn supports anupper arm 6130 through a bearing arrangement 6132 allowing rotation ofupper arm 6130 about a horizontal axis extending along the length of arm6130. Upper arm 6130 supports a cassette 6134 containing a flat paneldetector of the type discussed in the U.S. patents cited above. Cassette6134 can be connected to upper arm 6130 through a bearing arrangement6136 to allow rotation of cassette 6134 about an axis normal to thex-ray receiving face of the flat panel detector. This can be desirableif the panel inside cassette 6134 is rectangular, to allow using it inportrait or landscape orientations, or if such rotation is desirable forother reasons. Alternatively, bearing arrangement 6136 can be omitted. Ahandle 6138 is attached to cassette 6134, when bearing 6136 is used, orcan be attached directly to arm 6130 otherwise, and has a manual switch6138 a at its distal end that locks cassette 6134 in position or unlocksit to allow repositioning, or comprises several switches or othercontrols used for other purposes, such as to control motorizedmovements.

A patient table 6140 is supported on a telescoping column 6142 thatmoves table 6140 up and down, along the z-axis, within a guide 6144secured to main support 6110. Table 6140 is made of a material thatminimizes distortion of the spatial distribution of x-rays passingthrough it. If desired, table 6140 can be made movable along the x-axis,in a manner similar to the bed in the QDR-4500 Acclaim systemcommercially available from the assignee of this patent specification,and/or can be made to tilt about one or both of the x-axis and they-axis. A console and display unit schematically illustrated at 6141 canbe connected by cable to cassette 6134 to supply power and controlsignals thereto and to receive digital image data therefrom (andpossibly other information) for processing and display. The display atunit 6141 can be, for example, on a CRT or a flat panel display screenused in the usual manner. The usual image manipulation facilities can beprovided at unit 6141, for example for level and window controls of thedisplayed digital x-ray image, for image magnification, etc. The cablingcan be run through column 6120 and through bearing arrangement 6118 andlower arm 6116 to reduce interference with motion of slide 6114 alongtrack 6112, rotation of arm 6116 about bearing 6118, and vertical motionof cassette 6134 along column 6120. Alternatively, cassette 6134 can bepowered and controlled in some other way, and image data can beextracted therefrom in some other way. For example, cassette 6134 can bea self-contained cassette, with an internal power supply and withcontrol switches on or in cassette 6134 can control its operation.Cassette 6134 can further contain storage for the data of one or morex-ray images. Image data can be taken out of cassette 6134 by way of awireless connection, or by temporarily plugging in a cable therein whenit is time to read image data.

For a chest AP image of a supine patient, table 6140 can be lowered tomake it easier for the patient to get on. Of course, cassette 6134 thathas to be in a position that allows table 6140 to be lowered. Otherwise,the operator trips switch 6138 a to release cassette 6134, and moves itto the appropriate position manually, using handle 6138 to slidevertical slide 6122 up or down along column 6120. Alternatively, or inaddition, the operator rotates lower arm 6116 about bearing 6118, forexample to the position shown in FIG. 62 or FIG. 63. With the patient inthe supine position, head at the left end of table 6140 as seen in FIG.61, the operator can leave table 6140 at that position, or can move itup to a higher position. Table 6140 can be moved up or down by drivingtelescoping column 6142 with a motorized drive similar to that used insaid QDR-4500 unit. Alternatively, another table elevating mechanism canbe used. The operator then moves cassette 6134 to a position such asshown in FIG. 61, under table 6140, vertically aligned with thepatient's chest. For that purpose, the operator trips switch 6138 a torelease cassette 6134, and manually moves cassette 6134 up or downcolumn 6120 to the desired height, and can manually rotate lower arm6116 about bearing 6118 and slide horizontal slide 6114 along track6112. An x-ray source schematically illustrated at 6146 can be separatefrom the bed and detector system, and is aligned with and faces cassette6134, and is energized in the usual way to produce the appropriate x-rayexposure at detector 6134. Source 6146 can be connected with console anddisplay unit 6141 in the usual way, through cable or a wirelessconnection, to allow controlling x-ray source 6146 from unit 6141. Unit6141 and x-ray source 6146 are not shown in the remaining figures, butit should be understood that they can be present there as well and arein the usual way for an x-ray exposure.

FIG. 61 a illustrates a modification to implement a system that isotherwise the same or at least similar to the embodiment of FIG. 61except for slide 6122 is secured to a telescoping column 6162 a movingup and down in a guide 6160 a instead of sliding along a column 6120 asin FIG. 61. In FIG. 61 a, telescoping column 6162 a carries slide 6122,and with it cassette 6134, up and down. This up and down movement can bedone by hand or can be motorized, and can use counterweights or someother arrangement to make hand actuation easier, and can use clutches,brakes, etc. as for other movements discussed herein. In all otherrespect, the system of FIG. 61 a is the same or at least similar to thatof FIG. 61, although only a part of the system is illustrated in FIG. 61a.

For imaging an arm or a hand, for example, cassette 6134 is positionedas illustrated in FIG. 62, by rotating lower arm 6116 about bearing6118, moving cassette 6134 up or down along column 6120 and, if desired,sliding horizontal slide 6114 along track 6112 as earlier described. Atthe desired height of cassette 6134, and of table 6140 with the patientthereon, x-ray source 6146 is aligned and energized in the usual way forx-ray exposure.

For imaging the head or lower extremities of a patient, table 6140 andcassette 6134 can be positioned as illustrated in FIG. 63, moving one orboth to the desired position using the motions described above, with thepatient's head or, for example, foot, resting on cassette 6134. Ifdesired, the operator can rotate cassette 6134 about an axis parallel tohandle 6138 to incline cassette 6134, for example through an anglerelative to the vertical, as illustrated in FIG. 63. X-ray source 6146is aligned and energized the usual way.

FIG. 64 illustrates cassette 6134 moved to a position away from patienttable 6140, suitable for use with a patient in a wheelchair, forexample. Cassette 6134 is positioned relative to the patient using someor all of the motions earlier described, and an x-ray exposure is taken.

In FIG. 65, cassette 6134 is oriented vertically, by releasing itthrough manual operation of switch 6138 a and rotating about bearing6132, in addition to some or all of the cassette and/or table motionsearlier described. An x-ray source 6146 (not shown in this figure) facescassette 6134 from across patient table 6140 and is aligned andenergized in the usual manner for an exposure.

FIG. 66 illustrates cassette 6134 in a vertical orientation, for examplefor an AP chest image of a standing patient. The operator moves cassette6134 to the illustrated position using some or all of the motionsearlier described to align cassette 6134 with the patient's chest. Anx-ray source (not shown in this figure) that faces cassette 6134 fromacross the patient is aligned and energized in the usual way for anexposure.

FIG. 67 illustrates another position of cassette 6134 that can also beused for imaging the chest of a standing patient. It differs only inthat, while in FIG. 66 lower arm 6116 extends along the same x-axis astrack 6112, in FIG. 67 arm 6116 is normal to track 6112.

FIG. 68 illustrates cassette 6134 in a position suitable, for example,for imaging a lower extremity of a standing patient. Using some or allof the motions earlier described, the operator moves cassette 6134 tothe illustrated position, aligned with the patient part to be imaged,and the suitably aligned x-ray source (not shown in this figure) isenergized for an exposure. Patient table 6140 is not shown in FIG. 68.It may, but need not, be present in all of the embodiments disclosedherein. For example, if there is no need to support a patient on apatient table, then table 6140 and its telescoping support 6142 andguide 6144 can be omitted, or can be offered only as an option to thearrangement shown in FIG. 68.

FIG. 69 illustrates an alternative arrangement that differs from FIG. 61in that a telescoping, horizontally extending rail 6148 secured to mainsupport 6110 moves column 6120 along the x-axis, instead of using ahorizontal slide 6114 riding on a track 6112 as in FIG. 61. Column 6120can be moved in the y-direction using a sliding arrangement to permit itto move along the x-axis relative to rail 6148. Alternatively, rail 6148can be pivotally mounted on support 6144 to allow it to pivot about thez-axis and thus move column 6120 in a direction transverse to thex-axis. Unit 6141 and x-ray source 6146 are not shown in FIG. 69 but canbe present.

FIG. 70 illustrates yet another embodiment differing from FIG. 61 inthat table 6140 is supported on two columns 6150 that could betelescoping for movement along the z-axis, and column 6120 is supportedon a bracket 6152 that is in turn supported on a plate 6154. A mainsupport 6156 has tracks 6158 supporting plate 6154 for movement alongthe x-axis. Bracket 6152 can be pivotally mounted, for rotation ofcolumn 6120 about a vertical axis, and can be mounted on tracks on plate6154, for motion of column 6120 along the y-axis. Handles 6160, 6162 canbe provided on or at cassette 6134 to help in manually positioning thecassette.

Using the motions previously described, the operator can positioncassette 6134 in the embodiments of FIGS. 69 and 70 in a similar varietyof positions, for similar x-ray imaging procedures. While an x-raysource and a unit 6141 are not shown in FIGS. 69 and 70, it should beunderstood that they can be present and can be used as earlierdescribed.

In each embodiment, electronic, electromechanical and/or mechanicalbrakes and clutches can be used to immobilize and release theconnections between parts that can move relative to each other. Usingsuch brakes and clutches can allow the operator to move cassette 6134 tothe desired position manually with ease, and can securely fix cassette6134 in a position for exposure. For example, the operator can tripswitch 6138 a to engage such clutch or clutches and/or brake or brakesto thereby allow motion, and can trip the switch to disengage suchclutch(es) and/or brake(s) to thereby prevent motion. Such a clutchand/or brake arrangement can be used for one or more of the motionsdescribed above. Separate such arrangements can be used for differentones of the motions.

To facilitate the selection of a position for cassette 6134, variousdetents and indicators can be provided. For example, in the embodimentof FIGS. 61-68 a detent can be provided at bearing arrangement 6118 toreleasably lock arm 6116 at each 90° position along the x-axis andy-axis (and/or at different angular positions). A similar detent can beprovided at bearing 6132 for each 15° of a movement (or a differentangular increment) of cassette 6134 over a 180° rotation.

Instead of manually moving cassette 6134 to the desired position asdescribed above, respective electric or other motors can be used todrive some or all of the motions discussed above, under operatorcontrol. Alternatively, some or all of the motions can be automated, sothat the operator can select one of several preset motion sequences, orcan select vertical, horizontal and angular positions for cassette 6134,and computer controls can provide the necessary motor control commands.Particularly when movements are power-driven rather than manual,proximity and/or impact sensors can be used at the moving parts as asafety measure, generating stop-motion signals when a moving part getstoo close to, or impacts with, an object or a patient.

Cassette 6134 can contain a flat panel detector that converts x-raysdirectly into electrical signals representing the x-ray image, using adetection layer containing selenium, silicon or lead oxide.Alternatively, cassette 6134 can contain a flat panel detector that usesa scintillating material layer on which the x-rays impinge to generate alight pattern and an array of devices responsive to the light pattern togenerate electrical signals representing the x-ray image.

The disclosed system can be used for tomosynthesis motion, where thex-ray source and the cassette move relative to each other and thepatient, or at least one of the source and cassette moves, either in acontinuous motion or in a step-and-shoot manner. The image informationacquired at each step (or each time increment) can be read out and thedetector reset for an image at the next step (or time increment).

The disclosed system provides for a number of motions to accommodate awide variety of imaging protocols: the x-ray detector image planerotates between vertical and horizontal and can be locked atintermediate angles as well; the cassette moves horizontally along thelength of the patient table as well as across the length of the patienttable so that it can be positioned at either side of the table; thecassette moves vertically, the cassette can move between portrait andlandscape orientations for non-square detector arrays and/or for desiredorientation of the array grid even for square arrays; and the cassettecan combine some or all of these motions in order to get to any desiredposition and orientation.

Safety can be enhanced by moving the cassette by hand, so the operatorcan observe all motion and ensure safety. Sensors can be provided forcollision detection when any motion is motorized. When any motion ismotorized, easy-stall motors can be used to enhance safety. In addition,when any motion is motorized, encoders can be provided to keep track ofthe positions of moving components, and the encoder outputs can be usedfor software tracking and collision avoidance control. When motions aremotorized, preset motor controls can be stored in a computer and used todrive the cassette motion for specified imaging protocols or cassettepositions so that the cassette can automatically move to a presetposition for a given imaging protocol. Undesirable motion can be avoidedor reduced by using clutch controls, hand brakes, counter-balancing,and/or detents that help identify and maintain a desired cassetteposition and orientation and help prevent grid oscillation and focusinggrid misalignment.

FIG. 71 illustrates another embodiment that is particularly suitable foruse without a permanent patient bed, although one could be used. A flatpanel x-ray image receptor 34 that incorporates a Bucky assembly ismounted to an upright column 710 such that it can rotate betweenportrait and landscape orientations, tilt between vertical andhorizontal orientations of its imaging front surface, translate up anddown column 710, and rotate together with column 710 about the longcolumn axis. Column 710 can be bolted to the floor of the x-ray room, asillustrated, or can be on a movable support (not shown). An x-ray source712 is supported by a telescoping column 714 mounted on a ceiling track,to move with several degrees of freedom as is conventional in hospitalx-ray rooms, so that the x-ray beam therefrom can be directed to thereceptor 34 at any desired position thereof. Alternatively, the x-raysource can be otherwise supported such as, without limitation, on thefloor or on a movable cart.

Column 710 car rotate about its long axis on a bearing 716, and receptor34 follows that rotation. In addition, receptor 34 cam move up and downcolumn 710 in a manner similar to that described in earlier embodiments.Also as described in earlier embodiments, receptor 34 can rotate about ahorizontal axis on a bearing 718, and can rotate about an axistransverse to a centrally located relative to its x-ray detecting faceabout a pivot point not seen in FIG. 71. Other mechanisms described inconnection with receptor 34 in earlier embodiments such as, withoutlimitation, motorized motions, motion encoders, detents, etc., can beused in embodiment of FIG. 71 as well.

FIG. 72 illustrates an embodiment where an x-ray source 720 is suspendedfrom ceiling tracks (not shown) on a telescoping column 722 as common inx-ray rooms, and flat panel x-ray receptor 724 is also suspended fromits own ceiling tracks on a similar telescoping column 726.Alternatively, columns 722 and 726 can be supported on tracks that arein turn supported on some structures that are wall or floor supported.The tracks along which telescoping columns 722 and 726 preferably areindependent of each other so that the x-ray source and receptor can movealong respective independent paths. For example, column 722 can movealong a ceiling track 728 while column 726 moves along a ceiling track730 that is independent and separate from track 728. Column 726 cantelescope to adjust the vertical position of receptor 726. A support forreceptor 724 can pivot about a vertical axis on a bearing 732 and abouta horizontal axis on a bearing 734. In addition, as in earlierembodiments, receptor 724 can pivot about a central axis transverse toits imaging face, and its motions can be associated with some or all ofthe improvements earlier discussed. No permanent patient bed is requiredfor this embodiment. The patient can be on a gurney 736 or can be on awheelchair or can stand or otherwise be positioned for imaging.

FIG. 73 illustrated an embodiment in which a flat panel x-ray receptor730 that is otherwise similar to the receptors discussed with earlierembodiments can be used with a gurney or patient bed 732 or can beremoved for use otherwise such as, without limitation, on a wall or heldby the patient. In this embodiment, gurney 732 has a slot 734 that issimilar to a slot for a desk drawer, dimensioned and otherwise adaptedto receive receptor 730 as illustrated. A matching slot, not numbered,is provided at the other side of gurney 732, and one or more supportingrails are provided centrally in gurney 732 to support receptor 730 inthe illustrated horizontal position while allowing it to slide along thelength of gurney 732 to the extent allowed by the slots therein. Aportable x-ray source unit 736 can be used, as is common in hospitalsand similar venues. Receptor 730 can be removed from gurney 732 andsupported otherwise for some x-ray protocols B for example, receptor 730can be hung on a wall or some other support, or can be held by thepatient.

In all of the embodiments disclosed above, features of one can be usedin combination with features of others. As a non-limiting example,gurney 732 and receptor 739 can be used with a different x-ray source,for example a ceiling supported source such as illustrated in FIGS. 71and 72, and some or all of the motion aids (detents, motors, encoders,etc.) earlier described can be used in any of the embodiments.

It should be clear that the embodiments described above are onlyillustrative and many variations and modification thereof are within thescope of the inventions defined in the appended claims.

1. A system positioning a digital flat panel x-ray receptor for avariety of diagnostic x-ray protocols, comprising: at least one x-raysource selectively emitting an x-ray beam; a digital flat panel x-rayreceptor having an imaging face; an upwardly extending, floor-supportedcolumn supporting the receptor for movement to different positionswherein the receptor moves in at least two translational and threerotational motions; said receptor and at least one x-ray source beingmounted on separate supports for movement independent of each other; andsaid at least one x-ray source and said receptor being juxtaposed fordirecting said x-ray beam to said imaging face of the receptor for avariety of diagnostic x-ray protocols.
 2. A system as in claim 1,wherein the receptor has at least five degrees of freedom relative tothe column.
 3. A system as in claim 1, further including motorizeddrivers for moving the receptor.
 4. A system as in claim 1, furtherincluding encoders coupled with the column to provide digitalinformation regarding movement thereof, and a computer coupled with theencoders to receive digital information therefrom and programmed toutilize the information to control said movement.
 5. A system as inclaim 1, wherein said variety of diagnostic x-ray protocols includeprotocols in which the source is above the receptor and protocols forlateral imaging in which the source and receptor are at matching levels.6. A system as in claim 1, wherein the movement of said receptor in atleast two translational and three rotational motions includes rotationbetween portrait and landscape orientations, tilt between vertical andhorizontal orientations of the imaging face of said receptor, rotationtogether with said column about a long column axis, and translation upand down said column.
 7. A system positioning a digital flat panel x-rayreceptor for a variety of diagnostic x-ray protocols, comprising: atleast one x-ray source selectively emitting an x-ray beam; a digitalflat panel x-ray receptor having an imaging face; an upwardly extending,floor-supported column supporting the receptor for movement to differentpositions, wherein the receptor moves in at least two translational andthree rotational motions, including up and down along an upwardlyextending axis, about the same or a different upwardly extending axis,and about a lateral axis transverse to the axis along which the receptormoves up and down; said receptor and at least one x-ray source beingmounted on separate supports for movement independent of each other; andsaid at least one x-ray source and said receptor being juxtaposed fordirecting said x-ray beam to said imaging face of the receptor for avariety of diagnostic x-ray protocols.
 8. A system as in claim 7,further including motorized drivers for moving the receptor.
 9. A systemas in claim 7, further including encoders coupled with the column toprovide digital information regarding movement thereof, and a computercoupled with the encoders to receive digital information therefrom andprogrammed to utilize the information to control said movement.
 10. Asystem as in claim 7, wherein the movement of said receptor in at leasttwo translational and three rotational motions includes rotation betweenportrait and landscape orientations, tilt between vertical andhorizontal orientations of the imaging face of said receptor, rotationtogether with said column about a long column axis, and translation upand down said column.
 11. A system positioning a digital flat panelx-ray receptor for a variety of diagnostic x-ray protocols, comprising:an x-ray source selectively emitting an x-ray beam and positioning saidbeam at positions and orientations for a variety of x-ray imagingprotocols, and a supporting structure for said x-ray source; a digitalflat panel x-ray receptor having an imaging face; a track supporting,for movement along the track, a downwardly extending, telescoping columnthat in turn supports said receptor for movement to position and orientsaid imaging face of the receptor to match the position and orientationof said x-ray beam for said variety of x-ray imaging protocols, whereinthe receptor moves in at least two translational and three rotationalmotions; said track being spaced from said supporting structure for thex-ray source to allow movement of said column along the track that isindependent of movement of the x-ray source or the support thereof. 12.A system as in claim 11, wherein said variety of x-ray imaging protocolsare f or standing, sitting and recumbent patients, including protocolsin which the source is above the receptor and protocols for lateralimaging in which the source and receptor are at matching levels.
 13. Asystem as in claim 11, wherein the movement of said receptor in at leasttwo translational and three rotational motions includes rotation betweenportrait and landscape orientations, tilt between vertical andhorizontal orientations of the imaging face of said receptor, rotationtogether with said column about a long column axis, and translation upand down said column.
 14. A system positioning a digital flat panelx-ray receptor for a variety of diagnostic x-ray protocols, comprising:an x-ray source selectively emitting an x-ray beam and positioning saidbeam at positions and orientations for a variety of x-ray imagingprotocols, and a supporting structure for said x-ray source; a digitalflat panel x-ray receptor having an imaging face; a track supporting,for movement along the track, a downwardly extending, telescoping columnthat in turn supports said receptor for movement to match the positionand orientation of said x-ray beam for said variety of x-ray imagingprotocols, wherein the receptor moves in at least two translational andthree rotational motions, including up and down, about an up-down axis,and about a lateral axis transverse to said up-down axis.
 15. A systemas in claim 14, further including motorized drivers for moving thereceptor.
 16. A system as in claim 14, further including encoderscoupled with the column to provide digital information regardingmovement thereof, and a computer coupled with the encoders to receivedigital information therefrom and programmed to utilize the informationto control said movement.
 17. A system as in claim 14, wherein themovement of said receptor in at least two translational and threerotational motions includes rotation between portrait and landscapeorientations, tilt between vertical and horizontal orientations of theimaging face of said receptor, rotation together with said column abouta long column axis, and translation up and down said column.
 18. Asystem positioning a digital flat panel x-ray receptor for a variety ofdiagnostic x-ray protocols, comprising: an x-ray source selectivelyemitting an x-ray beam; a digital flat panel x-ray receptor having animaging face; a first track supporting, for movement along the firsttrack, a first downwardly extending, telescoping column that in turnsupports said source for movement up and down, about a first up-downaxis, and about a first lateral axis transverse to said first up-downaxis, to thereby position and orient said x-ray beam for a variety ofx-ray imaging protocols; a second track supporting, for movement alongthe second track, a second, downwardly extending, telescoping columnthat in turn supports said receptor for movement to position and orientsaid imaging face of the receptor to match the position and orientationof said x-ray beam for said variety of x-ray imaging protocols, whereinthe receptor moves in at least two translational and three rotationalmotions; said first and second tracks being spaced from each other toallow movement of said first column along the first track that isindependent of movement of the second column along the second track. 19.A system as in claim 18, wherein said variety of x-ray imaging protocolsare for standing, sitting and recumbent patients, including protocols inwhich the source is above the receptor and protocols for lateral imagingin which the source and receptor are at matching levels.
 20. A system asin claim 18, wherein the movement of said receptor in at least twotranslational and three rotational motions includes rotation betweenportrait and landscape orientations, tilt between vertical andhorizontal orientations of the imaging face of said receptor, rotationtogether with said second column about a long column axis, andtranslation up and down said second column.
 21. A system positioning adigital flat panel x-ray receptor for a variety of diagnostic x-rayprotocols, comprising: an x-ray source selectively emitting an x-raybeam; a digital flat panel x-ray receptor having an imaging face; afirst track supporting, f or movement along the first track, a firstdownwardly extending, telescoping column that in turn supports saidsource for movement up and down, about a first up-down axis, and about afirst lateral axis transverse to said first up-down axis, to therebyposition and orient said x-ray beam for a variety of x-ray imagingprotocols; a second track supporting, for movement along the secondtrack, a second, downwardly extending, telescoping column that in turnsupports said receptor for movement to position and orient said imagingface of the receptor to match the position and orientation of said x-raybeam for said variety of x-ray imaging protocols, wherein the receptormoves in at least two translational and three rotational motions,including up and down, about a second up-down axis, and about a secondlateral axis transverse to said second up-down axis.
 22. A system as inclaim 21, further including motorized drivers for moving the receptor.23. A system as in claim 21, further including encoders coupled with thecolumn to provide digital information regarding movement thereof, and acomputer coupled with the encoders to receive digital informationtherefrom and programmed to utilize the information to control saidmovement.
 24. A system as in claim 21, wherein the movement of saidreceptor in at least two translational and three rotational motionsincludes rotation between portrait and landscape orientations, tiltbetween vertical and horizontal orientations of the imaging face of saidreceptor, rotation together with said second column about a long columnaxis, and translation up and down said second column.